輸入和輸出迭代器

Question

我有一個關於使用輸入和輸出迭代器的練習題。功能的標題是如下

template<class InpIter,class OutpIter> 
OutpIter my_unique_copy(InpIter first, InpIter last, OutpIter result) 

該函數應的元素從所述範圍複製[第一，最後]導致。在連續的重複元素組中，只有第一個值被複制。返回值是元素複製到的範圍的末尾。 複雜性：線性

我有一個想法，做剛琢磨了一點幫助，因爲我不是迭代器舒適又不失

template<class InpIter,class OutpIter> 
OutpIter my_unique_copy(InpIter first, InpIter last, OutpIter result){ 
    InpIter current=first; 
    first++;//point to second element 
    while(first!=last){ 
     while(*first==*current){//Keep comparing elements to current to see if they're same 
      first++; 
     } 
     result=current; 
     current=first; 
     result++; 
     first++; 
    } 
    return result; 
} 

Answer 1

我想這是你所追求的，什麼每一步的解釋。

template<class InpIter,class OutpIter> 
OutpIter my_unique_copy(InpIter first, InpIter last, OutpIter result) 
{ 
    // keep going until end of sequence 
    while(first!=last) 
    { 
     // save current position. 
     InpIter current=first; 

     // advance first, test it against last, and if not 
     // equal, test what it references against current. 
     // repeat this until *first != *current, or first == last 
     while (++first != last && *first == *current); 

     // not matter what dropped the loop above, we still have 
     // our current, so save it off and advance result. 
     *result++ = *current; 
    } 

    // not sure why you want to return the first iterator position 
    // *past* the last insertion, but I kept this as-is regardless. 
    return result; 
} 

我希望能解釋一下。 （我不認爲我錯過了什麼，但我敢肯定，我會聽到它，如果我做到了。）

一個非常簡單的測試工具：

#include <iostream> 
#include <iterator> 
#include <algorithm> 

int main() 
{ 
    int ar[] = { 1,2,2,3,3,3,4,5,5,6,7,7,7,7,8 }; 
    int res[10] = {0}; 

    int *p = my_unique_copy(std::begin(ar), std::end(ar), res); 
    std::copy(res, p, std::ostream_iterator<int>(std::cout, " ")); 
    return 0; 
} 

輸出

1 2 3 4 5 6 7 8